Dr Tim Evans is a busy man. He is the Queen’s GP – Apothecary to Her Majesty and the Royal Household, to be precise – and when we first meet he has come straight from Buckingham Palace, where he has a surgery tending not just to our sovereign but all of her staff. He is bouncy, keen, fantastically calm, his tranquility hiding what must be some of the most fascinating medical secrets on the planet – but of course the 57-year-old is extremely discreet.

On top of his work commitments he is a single father to Wilf, 11, and Poppy, who is about to turn 10. His wife, Annabel, died at the end of 2008, after a long illness. She had “a very aggressive breast cancer” and was dead within five years of her diagnosis, which took place when Poppy was just 11 months old and Annabel was pregnant with their third child. “It wasn’t on the radar,” he says. “We weren’t even thinking about breast cancer and terminal disease. Perhaps you do take the eye off the ball when you’re in baby mode. Although in the back of her head she probably knew that she was 38 and that was the age at which her mother got breast cancer. But we were going for our third child, and she was pregnant, and then she discovered the lump.” Annabel miscarried soon after, and Dr Evans seems almost grateful for that. “Otherwise she would never have terminated the pregnancy, and she would have died very quickly.”

He is to the point about what happened. The situation is “horrible”, he says, “but I’ve got two children and they are fantastic and the most important thing for me is to be able to see them.”

Dr Evans is not your average GP, scribbling out prescriptions in a harassed manner, desperate to get each patient out through the door. Unlike traditional doctors, he is passionate about complementary therapies, which made him a controversial choice when he was appointed as the Queen’s doctor eight years ago – although Her Majesty is believed to be a fan of complementary therapies. He has had colonic hydrotherapy (“it wasn’t nearly as bad as I thought it would be”), raves about acupuncture (it has almost completely got rid of his hay fever) and thinks osteopathy is great. “But there’s not a lot of evidence behind homeopathy, which is a shame.”

He says he takes a “holistic approach” to things and goes in for “functional medicine, where we look at the patient, not the illness – it is about prevention, not cure. I have always been an integrated doctor, even when I didn’t realise it.”

One of his grandfathers was a surgeon, the other a physician at St Thomas’s. His father was an orthopaedic surgeon, his mother a nurse. After qualifying, he went to Zimbabwe to help run a hospital in the Zambezi Valley, which to his family seemed like him giving up, because all of his contemporaries were knuckling down and getting into their specialisms. “But it was an extraordinary experience,” he says, and he credits his three years there for developing the approach he takes to medicine now. “I learnt on the job from some very experienced third world doctors,” he explains, “but I also had to work alongside the witch doctor.”

In remote African communities, you have to, he says. “You can’t undermine them, you work with them. The potions and lotions and the poisons…” He shakes his head. “Well, it was extraordinary. And I found it at times frustrating to have certain things burning in the corner when a child was dying of measles and it was never going to work.”

But he had so many amazing experiences that broadened his medical expertise. “Elephant tramplings and lion attacks, and missing bottoms because the hippos had just bitten them off. I worked on Lake Kariba, so there were a lot of hippo bites,” he says, as if this was the most normal thing in the world. “It was 1983, I was there for the beginning of Aids. At one point, I had three cases of Kaposi’s sarcoma, which I had never seen, because it is a really rare Aids-related skin cancer. These three men were dying of Aids, but we didn’t know what it was.”

When he came back to the UK, he decided to set up his own private general practice. “I wanted it to be that, instead of paying every time you came, you paid a membership – like a primary health-care insurance scheme, underwritten by myself.”

At first, nobody came. “I was doing it out of a room in my house in Fulham, and I had the biggest appointment diary you could buy, with zero patients.”

Eventually they trickled in, and soon he had 50 patients (“which meant I was earning £15,000 a year”), gradually gaining more by word of mouth.

“I made everyone have a medical every year. They could come as often as they liked, but my incentive was to keep them well, so they didn’t come back all the time. That was a real Chinese philosophy, that you pay someone in order to be kept healthy.”

He made sure communication was at the heart of what he did. “You have to connect with your patient, be able to extract their history, because 90 per cent of any diagnosis is made from history alone. So if you don’t have that communication, you don’t get the full story, and then you’re guessing, which means you’re into veterinary medicine. You might as well be treating a horse.”

And now he is about to become the medical director of a new women’s-only integrated health club, located a stone’s throw from the Palace. This means that, for a price, we can all be treated like the Queen. At Grace, Evans will oversee a team of about 20, from gynaecologists to cardiologists to dermatologists, all of them female. Will it be like Tim’s Angels? “That’s exactly what it will be like,” he laughs. “And they are angels, because I couldn’t do without them.”

But Dr Evans says that his work has always been female-orientated. When he worked out of his house way back when, most of his patients were mothers and their children. “I think women are more interesting medically,” he explains. “They are a fascinating, challenging and rewarding group of patients because they go through all of these changes, from adolescence through to young motherhood and beyond.”

How does he do it, what with looking after the Queen and taking on a whole raft of new patients at Grace? “Well,” he laughs, “last night, I got home at 1.30am and went to wake the children up so they knew I was there, and then I woke them up at 6.30am and took them to school and then came back here to do an interview with you.

“Life,” he smiles, “is a balancing act.” And with that, he is off to his next appointment.